This invention relates generally to drawer slides, and more particularly to drawer slides having detent mechanisms.
Drawer slides for file drawers, shelves, and the like are often desirable for use in cabinets, desks, and rack-mounted applications. Such slides permit easy access to the interior of a drawer or to the top of a shelf. The slides maintain the drawer or shelf in a horizontal position regardless of how far the drawer or shelf is withdrawn from the cabinet or desk.
A typical drawer slide has two or three slide members slidably coupled by sets of bearings, which are often ball bearings. The bearings generally roll in raceways formed on the slide members. The slide member attached to the cabinet or desk, which may be viewed as a stationary frame, generally comprises a longitudinally elongated substantially planar web with bearing raceways extending from the margins of and along the length of the web. The slide member attached to the drawer or shelf, which may be viewed as a moveable object, also generally comprises a longitudinally elongated substantially planar web with bearing raceways along the length of the web extending from the margins of and along the length of the web.
In a three-drawer slide, an intermediate member is disposed between the slide member attached to the stationary frame and the slide member attached to the moveable object. The intermediate member is sometimes similarly shaped, depending on the type of drawer slide, as drawer slides come in a variety of types. For example, in a telescopic drawer slide, the slide members are generally nested within one another and the intermediate slide member is substantially similar to the other slide members. In an over and under drawer slide, however, two of the drawer slides are arranged in a vertical plane, and the intermediate drawer slide member generally has a pair of offset webs connected by a connecting member.
When drawer slides are used to extensibly mount a cabinet or shelf with respect to a stationary frame, it is often desirable to partially restrain movement of the drawer slide members with respect to one another when the drawer slide members are in pre-defined positions. For example, it is often desirable to partially restrain movement of the drawer slide members when the cabinet or shelf is in a retracted position with respect to the stationary frame. Such a partial restraint is sometimes termed a detent-in, as opposed to a detent-out which is a partial restraint in a fully extended position. Without such a partial restraint, the shelf or drawer may inadvertently extend due to the stationary frame being mounted on an uneven floor, the drawer slides being installed at slight angles, or possibly vibration of the stationary frame. Similarly, at times it is desirable to partially restrain movement of the shelf or drawer when the shelf or drawer is partially extended, or fully extended, from the stationary frame.
Partial restraint of movement of the drawer slides may be accomplished by providing a frictional interface between the drawer slide members. For example, a frictional interface may be formed on a telescopic drawer slide by using a stop bumper, which is an internal bumper mounted on an upturned flange at the end of a web of an outer drawer slide member and by decreasing the distance between the raceways at an end of the inner slide member. With such an arrangement, the bearing raceways of the inner slide member may contact the stop bumper on the web of the outer slide member so that increased force is required to place the slide in a retracted position or to extend the slide. Such an arrangement, however, suffers from the defect that the detent positions are limited to the extremes of the drawer slide travel, i.e. to a detent-in or a detent-out. Further, a single bumper can not be used to provide both a detent-in and a detent-out function. In addition, over time the contact between the bearing raceways and the stop member may deteriorate the ability of both to perform their required functions. Furthermore, such arrangements are not necessarily usable with slides, such as parallel drawer slides, other than telescopic drawer slides.